Molecular+Structures

A structural formula is a molecular model that uses letter symbols and bonds to show relative positions of atoms. It can generally be predicted by means of a Lewis Structure. The following steps can be used in drawing Lewis Structures.
 * 1) Predict the location of certain atoms. Hydrogen is always a terminal atom. The atom with the least attraction for electrons is the central atom.
 * 2) Find the total number of electrons available for bonding (valance electrons). If the structure is to represent a positive or negative polyatomic ion, the ion charge must be subtracted or added, respectively.
 * 3) Divide the total number of available electrons by 2 to obtain the number of bonding pairs.
 * 4) Place one bonding pair between the central atom and each terminal atom.
 * 5) To find the total number of lone pairs and pairs available for multiple bonding, subtract the number of bonding pairs used in step 4 from the number of bonding pairs determined in step 3. Place lone pairs around the terminal atoms to satisfy the octet rule. Assign remaining pairs to the central atom.
 * 6) If the central atom is not surrounded by four electron pairs, convert one or two lone pairs on the terminal atoms to a double or triple bond to the central atom.